***Update***
-When an app (stored in the SD card) got updated (via Play Store update), it'll be 'moved' back to phone storage. I got a shock yesterday that my phone storage only have 600+MB. upon investigation, I found those apps I previously moved in SD card, got moved back to phone storage. After I moved them back to SD card, all back to normal.
-and because of the above, I managed to 'discover' the root cause of laggy flash. Because my dolphin browser got updated, it got moved back to phone storage and surprisingly, flash videos played smoothly. now I moved back dolphin browser to SD card flash is laggy again. I suspect performance hit when running apps stored in SD card since the data transfer rate is reduced vs stored in phone memory